The NIEHS Program-Project: Lipid Peroxidation and Antioxidant Mechanisms brings together four experienced investigators who share an interest in the free radical chemistry and biology of lipids, peroxidation, antioxidants and mechanisms of cellular injury and protection. Environmental stress and lifestyle play an important role in diseases that contribute significantly to mortality in the United States. Cigarette smoking, alcohol consumption and poor diet combine with other environmental factors to affect the incidence of several diseases. The formation of oxidants is a hallmark of many of these diseases and lipid peroxidation is a common result of diverse environmental insults. Indeed, oxidative stress has been closely associated with the onset of pathologies as diverse as cancer and cardiovascular disease. Both chemical and physical factors in the environment promote lipid peroxidation and oxidative damage in biological systems. These processes lead to organ dysfunction, genotoxicity, and disease. Nevertheless, the underlying mechanisms linking environmental stresses with disease pathogenesis remain obscure. The studies proposed here will identify mechanisms of oxidative damage and injury for a variety of lipid precursors. This Program Project includes four research projects and one instrument core (proteomics/mass spectrometry) in a tightly knit group that will provide important insights into the role that oxidation and antioxidants play in human pathophysiology. Project 1 tests the hypothesis that the peroxidation of different lipid classes and molecular species has dramatically different consequences and lays out protocols for obtaining profiles of important products formed in peroxidation. Project 2 explores the chemistry and biology of eicosapentaenoic acid (EPA), a fatty acid prominent in fish oil, and explores the hypothesis that EPA oxidation products may contribute significantly to the biological properties of this fatty acid. Project 3 explores the chemistry and biology of electrophiles formed in lipid peroxidation by the use of high throughput screens and identifies protein targets of these electrophiles. Project 4 suggests that secondary electrophilic products of lipid oxidation play critical roles in oxidant-associated molecular pathologies and explores methodologies for identification and analysis of protein adducts of these electrophiles. All of the projects are highly collaborative and are highly dependent on the facility cores.